1. Field of the Invention
The invention relates to virtual data storage systems. The invention further relates to policies to control usage of data storage.
2. Background Art
In an existing virtual data storage system, a server, disk storage, and software together provide a buffer or cache between mainframe servers and tape storage systems. Instead of writing directly to a physical drive, mainframe workloads read and write to virtual drives created and maintained by the virtual storage system. The virtual storage system improves tape cartridge utilization in the tape storage systems by using co-located data sets.
The existing virtual storage system approaches have been successful for certain applications. However, their use has typically been limited to mainframe applications. As well, the virtual drives have been typically limited to appearing as tape volumes and drives, and scalability has also been somewhat limited. Still further, emulation and storage management aspects of the existing virtual storage system have had limited flexibility, typically requiring hard mappings of virtual volumes to physical locations on disks.
It would be desirable in a sophisticated data storage system to provide the ability to create multiple copies of a stored data object on different kinds of storage media. Further, it would be desirable to create and delete these copies based on a time based schedule. It would be further desirable for the time based schedule to be able to be started based on creation, modification, or access to the stored data object.
For the foregoing reasons, there is a need for an improved virtual data storage system that recognizes and addresses various limitations of the existing virtual data storage system.